Case insensitive comparison of strings in shell script

Question

The == operator is used to compare two strings in shell script. However, I want to compare two strings ignoring case, how can it be done? Is there any standard command for this?

Answer 1

In Bash, you can use parameter expansion to modify a string to all lower-/upper-case:

var1=TesT
var2=tEst

echo ${var1,,} ${var2,,}
echo ${var1^^} ${var2^^}